X Window system

The C-based X Window system [33] is almost ubiquitous on computers running under Unix-like operating systems (OSs). The X Window system has a client-server architecture, in which a single X server serves requests from different GUI applications (called X clients) through inter-process communication. Each application registers the types of events it wishes to handle with the X server, and also registers an event processing routine with each registered event type. When events associated with a window occur, the X server only sends events of registered types to the window, which in turn calls the corresponding processing routine. The X server handles events of unregistered types as the default. Wrapper toolkits are typically used to facilitate GUI development. GTK [10], one of the most popular toolkits, is used in this work. An embedded port of GTK, called GPE [11], is actively under development. In this study, we use the X Window system that comes with the Familiar project [30] and GTK-related libraries from the public Skiff cluster [31]. We use X/GTK to refer to the X Window system and GTK.